Bronchiectasis

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Bronchiectasis

Chapter Objectives

After reading this chapter, you will be able to:

• Describe the anatomic alterations of the lungs associated with bronchiectasis, including the following:

• Varicose (fusiform) form of bronchiectasis

• Cylindrical (tubular) form of bronchiectasis

• Cystic (saccular) form of bronchiectasis

• Differentiate between the following possible types of bronchiectasis:

• Acquired bronchiectasis

• Congenital bronchiectasis

• Describe the cardiopulmonary clinical manifestations associated with bronchiectasis.

• Describe the general management of bronchiectasis.

• Describe the clinical strategies and rationales of the SOAPs presented in the case study.

• Define key terms and complete self-assessment questions at the end of the chapter and on Evolve.

Key Terms

Anatomic Alterations of the Lungs

Bronchiectasis is characterized by chronic dilation and distortion of one or more bronchi as a result of extensive inflammation and destruction of the bronchial wall cartilage, blood vessels, elastic tissue, and smooth muscle components. One or both lungs may be involved. Bronchiectasis is commonly limited to a lobe or segment and is frequently found in the lower lobes. The smaller bronchi, with less supporting cartilage, are predominantly affected.

Because of bronchial wall destruction, the mucociliary clearance mechanism is impaired. This results in the accumulation of copious amounts of bronchial secretions and blood that often become foul-smelling because of secondary colonization with anaerobic organisms. This condition may lead to secondary bronchial smooth muscle constriction and fibrosis. The small bronchi and bronchioles distal to the affected areas become partially or totally obstructed with secretions. This condition leads to one or both of the following anatomic alterations: (1) hyperinflation of the distal alveoli as a result of expiratory check-valve obstruction or (2) atelectasis, consolidation, and fibrosis as a result of complete bronchial obstruction.

Three forms or anatomic varieties of bronchiectasis have been described: cylindrical (tubular), varicose (fusiform), and cystic (saccular).

Cystic Bronchiectasis (Saccular Bronchiectasis)

In cystic (saccular) bronchiectasis, the bronchi progressively increase in diameter until they end in large, cystlike sacs in the lung parenchyma. This form of bronchiectasis causes the greatest damage to the tracheobronchial tree. The bronchial walls become composed of fibrous tissue alone—cartilage, elastic tissue, and smooth muscle are all absent (see Figure 13-1, C).

The following are the major pathologic or structural changes associated with bronchiectasis:

Etiology and Epidemiology

Bronchiectasis is not as common today as it was a few decades ago because of increased use of antibiotics for lower respiratory infections. The underlying cause of bronchiectasis is not known in more than 60% of the cases. Bronchiectasis is commonly classified by cause as being either acquired bronchiectasis or congenital bronchiectasis.

Acquired Bronchiectasis

Recurrent Pulmonary Infection

Bronchiectasis is commonly seen in individuals who have recurrent and prolonged episodes of lower respiratory tract infections (e.g., pneumonia, tuberculosis, and fungal infections). For example, children who have frequent bouts of bronchopneumonia—because of the respiratory complications of measles, chickenpox, whooping cough, or influenza—may acquire some form of bronchiectasis later in life.

Congenital Bronchiectasis

Cystic Fibrosis

It is estimated that cystic fibrosis causes approximately 50% of the bronchiectasis cases in the United States today. Because of the impairment of the mucociliary clearance mechanism—and the abundance of stagnant, thick mucus—associated with cystic fibrosis, bronchial obstruction from mucous plugging and bronchial wall infection frequently result. The necrotizing inflammation that develops under these conditions often leads to secondary bronchiectasis.

Kartagener’s Syndrome

Kartagener’s syndrome (also known as Kartagener’s triad, Siewert’s syndrome, dextrocardia-bronchiectasis-sinusitis syndrome, primary ciliary dyskinesia [PCD], and immotile ciliary syndrome) is an autosomal recessive genetic disorder. Kartagener’s syndrome is described as a triad disorder consisting of bronchiectasis, dextrocardia (having the heart on the right side of the chest), and rhinosinusitis. Patients with Kartagener’s syndrome have defective cilia lining throughout the respiratory tract, lower and upper sinuses, Eustachian tubes, middle ears, and fallopian tubes. Because of the defective cilia lining throughout the tracheobronchial tree, the patient is unable to adequately clear airway secretions and pathogenic bacteria. This condition leads to chronic mucous retention, recurrent respiratory tract infections, and damaged airway walls. Kartagener’s syndrome accounts for as much as 20% of all congenital bronchiectasis.

Systemic Disorders

Bronchiectasis is associated with several systemic conditions such as rheumatologic disorders, inflammatory bowel disease, and acquired immunodeficiency syndrome (AIDS).

image OVERVIEW of the Cardiopulmonary Clinical Manifestations Associated with Bronchiectasis

The following clinical manifestations result from the pathophysiologic mechanisms caused (or activated) by Excessive Bronchial Secretions (see Figure 9-12), Bronchospasm (see Figure 9-11), Atelectasis (see Figure 9-8), Consolidation (see Figure 9-9), and Increased Alveolar-Capillary Membrane Thickness) (See Figure 9-10)—the major anatomic alterations of the lungs associated with bronchiectasis (see Figure 13-1).

CLINICAL DATA OBTAINED AT THE PATIENT’S BEDSIDE

Depending on the amount of bronchial secretions and the degree of bronchial destruction and fibrosis associated with bronchiectasis, the disease may create an obstructive or a restrictive lung disorder or a combination of both. If the majority of the bronchial airways are only partially obstructed, the bronchiectasis manifests primarily as an obstructive lung disorder. If, on the other hand, the majority of the bronchial airways are completely obstructed, the distal alveoli collapse, atelectasis results, and the bronchiectasis manifests primarily as a restrictive disorder. Finally, if the disease is limited to a relatively small portion of the lung—as it often is—the patient may not have any of the following clinical manifestations.

The Physical Examination

Vital Signs

Increased Heart Rate (Pulse) and Blood Pressure

Cough, Sputum Production, and Hemoptysis

Chronic cough with production of large quantities of foul-smelling sputum is a hallmark of bronchiectasis. A 24-hour collection of sputum is usually voluminous and tends to settle into several different layers. Streaks of blood are seen frequently in the sputum, presumably originating from necrosis of the bronchial walls and erosion of bronchial blood vessels. Frank hemoptysis may also occur from time to time, but it is rarely life threatening. Because of the excessive bronchial secretions, secondary bacterial infections are frequent. Haemophilus influenzae, Streptococcus, Pseudomonas aeruginosa, and various anaerobic organisms are commonly cultured from the sputum of patients with bronchiectasis.

The productive cough in bronchiectasis is triggered by the large amount of secretions that fill the tracheobronchial tree. The stagnant secretions stimulate the subepithelial mechanoreceptors, which in turn produce a vagal reflex that triggers a cough. The subepithelial mechanoreceptors are found in the trachea, bronchi, and bronchioles, but they are predominantly located in the upper airways.

CLINICAL DATA OBTAINED FROM LABORATORY TESTS AND SPECIAL PROCEDURES

Pulmonary Function Test Findings

Moderate to Severe Bronchiectasis (When Primarily Obstructive Lung Pathophysiology)

FORCED EXPIRATORY FLOW RATE FINDINGS

FVC FEVT FEV1/FVC ratio FEF25%-75%
↓ ↓ ↓ ↓
FEF50% FEF200-1200 PEFR MVV
↓ ↓ ↓ ↓

image

LUNG VOLUME AND CAPACITY FINDINGS

VT IRV ERV RV  
N or ↑ N or ↓ N or ↓ ↑  
VC IC FRC TLC RV/TLC ratio
↓ N or ↓ ↑ N or ↑ N or ↑

image

Pulmonary Function Test Findings

Moderate to Severe Bronchiectasis (When Primarily Obstructive Lung Pathophysiology)

FORCED EXPIRATORY FLOW RATE FINDINGS

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FVC FEVT FEV1/FVC ratio FEF25%-75%
↓ N or ↓ N or ↑ N or ↓
FEF50% FEF200-1200 PEFR MVV
N or ↓ N or ↓

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